Lubrication of the moving parts of in-



United States Patent LUBRICATION OF THE MOVING PARTS OF IN- TERNAL COMBUSTION ENGRNES OPERATING ON SULFUR AND OXYGEN 0R OXYGEN-CON- TAINING GASES Gerhard Schachenmaier and Klaus Starke, Ludwigshafen (Rhine), Germany, assignors to Badische Anilin- & Soda Fabrik Aktiengesellschaft, Ludwigshafen (Rhine), Germany No Drawing. Filed Feb. 2, 1961, Ser. No. 86,573 Claims priority, application Germany Feb. 5, 1960 3 Claims. (Cl. 25231) The present invention relates to a method of lubricating the moving parts of internal combustion engines operating on sulfur and oxygen or oxygen-containing gases.

It is known to react sulfur with oxygen or oxygencontaining gases to sulfur dioxide in the combustion chamber of internal combustion engines and to directly convert the combustion heat evolved into mechanical energy.

If the moving parts of such internal combustion engines, where metal slides on metal, are lubricated with conventional lubricants, considerable trouble is caused, even after only short operating periods, by the small proportion of sulfur trioxide contained in the combustion gases. The sulfur trioxide attacks the lubricating oil with formation of organic sulfonic and sulfinic acids as well as the iron parts of the engine, as for example the piston rings and the Working surface of the cylinder, with formation of viscous, tar-containing and strongly acid-reacting products which contain iron in the form of cations and some of which are water-soluble. These viscous, greasy substances gum up the piston rings so that they can no longer perform their sealing function. This causes strong blowby into the crankcase and, as a result, the efficiency of the internal combustion engine is decreased considerably. The injurious effects produced by the sulfur trioxide contained in the combustion gases are aggravated by the action of sulfuric acid formed by the reaction of sulfur trioxide with water vapor which is contained in small amounts in the combustion gases and results from the combustion of lubricant.

We have found that the said disadvantages can be overcome by adding 0.05 to by weight of elementary sulfur to the lubricant used in the internal combustion engine and maintaining the inner cylinder wall of the internal combustion engine at a temperature above the dew point of sulfuric acid. The upper limit to the temperatures that may be employed depends on the material of the cylinder wall and on the lubricant used. Within the said limits, the temperatures may be varied at will. Depending on the temperature range as well as on the lubricant used, the sulfur added is present in the lubricant in dissolved form or in the form of a suspension or emulsion.

The portion of sulfur trioxide which comes into contact with the lubricant is reduced to sulfur dioxide by the elementary sulfur that has been added to the lubricant and is thus rendered innocuous.

In order to ensure that the temperature of the cylinder wall does not fall below the dew point of sulfuric acid, the temperature of the cooling medium used for indirect withdrawal of the heat of combustion is maintained at to 165 C., preferably at to C. If Water at atmospheric pressure is used as the coolant, agents for elevating the boiling point, such as glycol, glycerol and the like, must be added to the cooling water in order to achieve the said temperatures. If the cooling system of the internal combustion engine is of pressure-proof design, such additives may, however, be dispensed with, the heat being carried off as steam at 120 to C. and at a pressure of 2 to 7 atmospheres gage.

Thus a further advantage is offered by the method according to this invention in that, by rising the temperature of the coolant, a heat transfer medium is obtained whose temperature and heat content are sufficient to melt the sulfur which is to be burnt in the internal combustion engine as well as to maintain at an elevated temperature of preferably 145 to 155 C. the apparatus which is required for supplying, purifying and proportioning the molten sulfur.

What we claim is:

1. In the lubrication of moving parts of internal combustion engines operating on sulfur and a gas selected from the group consisting of O and o -containing gases, a method of inhibiting the formation of viscous substances and the corrosion of the moving parts which comprises using a lubricating oil which contains from 0.05 to 10% by weight of sulfur and maintaining the inner surface of the cylinder of the internal combustion engine at a temperature above the dew point of sulfuric acid and below 165 C. by means of a coolant.

2. A method as claimed in claim 1, wherein the coolant used is water to which has been added an agent for elevating the boiling point selected from the group consisting of glycol, glycerol and dimethyl sulfoxide.

3. A method as claimed in claim 1, wherein the coolant used is water which is maintained at a temperature of 120 to 165 C., preferably 145 to 155 C., by the application of pressure.

References Cited in the file. of this patent UNITED STATES PATENTS 2,222,431 Colin Nov. 19, 1940 2,231,939 Nallinger Feb. 18, 1941 2,581,050 Smedslund Jan. 1, 1952 2,767,693 Foutz Oct. 23, 1956 FOREIGN PATENTS 455,790 Great Britain Oct. 28, 1936 

1. IN THE LUBRICATION OF MOVING PARTS OF INTERNAL COMBUSTION ENGINES OPERATING ON SULFUR AND A GAS SELECTED FROM THE GROUP CONSISTING OF O2 AND OI-CONTAINING GASES, A METHOD OF INHIBITING THE FORMATION OF VISCOUS SUBSTANCES AND THE CORROSION OF THE MOVING PARTS WHICH COMPRISES USING A LUBRICATING OIL WHICH CONTAINS FROM 0.05 TO 10% BY WEIGHT OF SULFUR AND MAINTAINING THE INNER SURFACE OF THE CYLINDER OF THE INTERNAL COMBUSTION ENGINE AT A TEMPERATURE ABOVE THE DEW POINT OF SULFURIC ACID AND BELOW 165*C. BY MEANS OF A COOLANT. 